The Earth’s climate has changed many times during the planet’s history, with events ranging from ice ages to long periods of warmth. Historically, natural factors such as volcanic eruptions, changes in the Earth’s orbit, and the amount of energy released from the Sun have affected the Earth’s climate. DES’s Climate Change Web site offers comprehensive information on the issue of climate change in New Hampshire in a way that is accessible and meaningful to communities, individuals, business, and state and local government.

Life on Earth is possible because the Sun’s energy warms the earth and its atmosphere. As this warmth radiates back into space, a portion is absorbed by a delicate balance of heat-trapping greenhouse gases in the atmosphere, thus creating an insulating layer functioning similar to a conventional greenhouse. This "greenhouse effect" is a necessary natural global mechanism.

In the last 100 years, however, research indicates that the concentration of greenhouse gases, particularly carbon dioxide (CO2), has seen an unprecedented increase primarily due to the combustion of fossil fuels and urbanization of natural areas. Adding more heat-trapping gases to the atmosphere is causing global temperatures to increase. This increase in global temperatures is causing changes to the Earth's climatic system resulting in more variable and extreme weather conditions in various parts of the world.

Summary of New Hampshire Greenhouse Gas Emissions

New Hampshire’s greenhouse gas emissions include the following six major greenhouse gases:

Carbon dioxide (CO2)

Methane (CH4)

Nitrous oxide (N2O)

Hydrofluorocarbons (HFCs)

Perfluorocarbons (PFCs)

Sulfur hexafluoride (SF6)

These gases are generated from a variety of activities that are commonly categorized into sectors. The sectors include Transportation; Electric Generation; Agriculture, Forestry, and Waste; Residential; Commercial; and Industrial.

Carbon Dioxide (CO2) emissions make up the vast majority of NH’s greenhouse gas emissions (96 percent). They are generated by burning fossil fuels (oil, coal and gas) to produce heat and electricity, and to power motor vehicles. CO2 is emitted by all sectors.

The remaining greenhouse gases are generated by the Industrial, Agriculture, Forestry and Waste, and Transportation sectors. The synthetic gases (HFCs, PFCs and SF6) are generated during industrial processes. Methane (CH4) is generated by the decomposition of organic wastes in landfills, during the wastewater treatment process, and from livestock. Nitrous oxide (N2O) is generated from the production and use of fertilizers and from transportation sources.

Source: The EPA Greenhouse Gas Inventory

Source: The EPA Greenhouse Gas Inventory

Between 1990 and 1995, NH emissions remained relatively constant. By 2004, NH greenhouse gas emissions had increased by 48 percent over 1990 gross emission levels. Nearly 40 percent of this increase had occurred at the very end of the period due to growth in the Electric Generation sector.

Due to the amount of area in New Hampshire that is still dominated by forests, the NH landscape is actually a net carbon dioxide user (or sink). The process by which carbon is absorbed from the atmosphere and stored by plants is referred to as carbon sequestration. Carbon sequestration may absorb an amount equivalent to nearly 25 percent of CO2 emissions generated in NH. The charts above do not account for this carbon sequestration.